1. Field of the Invention
This invention relates to photographic elements having improved backing layer performance and to a method of preparing such photographic elements.
2. Description of Related Art
It is widely known in the art that various layers of photographic elements are formed on a suitable substrate commonly referred to in the art as a film support. Cellulose triacetate and polyesters such as polyethylene terephthalate and polyethylene naphthalate are materials which are commonly employed for this purpose. Polyester supports, primarily because of their hydrophobic nature, require the presence of one or more subbing layers (adhesion-promoting layers) on the surface of the support in order that the layers coated on the support will properly adhere thereto in further operations to which the photographic element is subjected.
The layers coated on the backside or the side opposite to that bearing the light-sensitive photographic emulsions, also usually contain an antistatic layer. Conductive metal oxides in a hydrophilic binder have been found extremely useful for this purpose.
U.S. Pat. No. 4,203,769 is directed to radiation sensitive elements having an amorphous vanadium pentoxide antistatic layer. This antistatic layer is disposed on the film support on the side opposite the light-sensitive emulsion layers. It is also-disclosed in this patent that when polyester film supports are employed, subbing layers such as that described in U.S. Pat. Nos. 2,627,088 and 2,779,684 may be employed as anchoring layers. The antistatic layer may also be overcoated with a protective layer containing cellulose ester materials such as cellulose ether phthalate, and cellulose acetobutyrate.
It has been found that when photographic elements are prepared on polyester film supports having the backing layers as outlined above, that upon processing through normal processing apparatus utilizing the C-41 development chemistry, minute blisters are formed which is a serious disadvantage in that it interferes with the optical characteristic of the photographic element. The C-41 process and chemistry are described in The British Journal of Photography Annual (1988), pages 191-207. These blisters can be defined as minute areas where a loss of adhesion occurs between adjacent layers. This loss of adhesion or delamination occurs during the photographic processing operation and may remain after drying of the processed photographic element. The blisters can collapse and form crater-like structures which can be observed optically.
Further, in certain embodiments of photographic elements, the cellulosic layer overlying the antistat layer may be a transparent magnetic recording layer containing ferromagnetic particles. This structure permits information to be written magnetically into the transparent magnetic recording layer for subsequent read-out and application. The formation of blisters or crater-like structures on the surface or at the interface of any of the layers present on the backside of the photographic element interferes with both the magnetic recording and readout of this transparent magnetic recording layer. Further, abrasion of the surface may readily occur as a direct result of this deficiency by contact with magnetic recording and reading heads.
Therefore, there is a need to provide photographic elements free of the disadvantages outlined above.